In the above-identified U.S. Pat. No. 4,597,082, there is disclosed a transceiver for multidrop local area networks for transmission over AC transmission lines, private wire, or other less noisy transmission channels that provides error free transmissions at very high data rates in noisy industrial environments at low cost.
In the above-identified application, Ser. No. 07/115,245, there is disclosed a transceiver system for communication over wire laid along the path of guided vehicles, wherein the transmission channel, is the typical floor loop used to guide such vehicles. In Ser. No. 07/309,272, filed Feb. 10, 1989, now U.S. Pat. No. 5,257,290 entitled Transmission Line Termination of Guide-Communications Wire For Guided Vehicles, the problem of null positions in such floor loops, at which the strength of signals sent from the host modem, is so low or non-existent that communications is impossible with the guided vehicle and one solution to that problem are discussed.
The present invention is directed to eliminating such multipath problems in wire guided vehicle applications and to combating periodic impulse and slowly time varying continuous wave noise typical of wire guided vehicles, power line carrier transmission systems and other transmission channels in an industrial environment.
While, according to the prior art, spread spectrum (frequency hopping) systems and time diversity techniques have been utilized to overcome transmission problems caused by random noise, which may be natural or caused by jamming, such techniques have not been utilized in low cost systems, which are oriented towards adaptive avoidance of inadvertent man-made noise, such as in the industrial environment. Such noise is time varying, but not truly random.